Geology and structure of Upheaval Dome, San Juan County, Utah: Salt or Impact Structure

Abstract

Upheaval Dome, San Juan County, Utah, is a complexly deformed circular structure approximately 5 km in diameter, occurring within the Triassic Moenkopi, Chinle, Wingate, and Kayenta and the Jurassic Navajo Formations. The structure shows three distinct zones of deformation. The brittlely deformed central crater exhibits an intensely compressional regime. It contains a multitude of sub-radial thrust faults and sedimentary intrusive dikes of the Permian White Rim, which exploit zones of weakness. The more ductilely deformed transitional area, which occurs between .5 km and 1.5 km from the center, is a generally compressional regime. This area includes small to large scale, sub-radial thrust and scissors faults, as well as folds extending radially from the center and concentrically encircling the structure. The exterior portion of the structure exhibits extensional features: two concentric, kilometer-scale folds, a monocline and syncline; and related small and large scale normal faults which structurally thin formations within the syncline. These faults are thought to link up with large scale faults in the transitional area, forming blocks which converged upon the center during the deformational event. Hypotheses formerly proposed for the structure’s origin include: a salt diapir; a salt diapir formed over a basement uplift; a hydrotectonic pressure release conduit; a buoyantly detached diapir; a cryptovolcanic feature; and a meteorite impact. Of these, the salt tectonic and impact models are the currently favored hypotheses. Though the detached salt diapir hypothesis adequately explains some of the features of the structure, it fails to explain others. In fact, non-structurally detached diapirs have never been observed in the field or the laboratory. The impact hypothesis is able to explain many of the structures present, but similarly sized and eroded craters have also never been found. Therefore, it is difficult to constrain Upheaval Dome’s origin to any one hypothesis.

Full text

Geology and structure of Upheaval Dome, San Juan
County, Utah: Salt or Impact Structure?
MIKE UNGER
SENIOR INTEGRATIVE EXERCISE
MARCH 10, 1995
PROFESSOR DAVID BICE, ADVISOR

GEOLOGY AND STRUCTURE OF UPHEAVAL DOME, SAN JUAN COUNTY,
UTAH: SALT OR IMPACT STRUCTURE?
Mike Unger
March 10, 1995
Professor David Bice, Advisor
Upheaval Dome, San Juan County, Utah, is a complexly deformed circular structure
approximately 5 km in diameter, occurring within the Triassic Moenkopi, Chinle,
Wingate, and Kayenta and the Jurassic Navajo Formations. The structure shows
three distinct zones of deformation. The brittlely deformed central crater exhibits
an intensely compressional regime. It contains a multitude of sub-radial thrust
faults and sedimentary intrusive dikes of the Permian White Rim, which exploit
zones of weakness. The more ductilely deformed transitional area, which occurs
between .5 km and 1.5 km from the center, is a generally compressional regime.
This area includes small to large scale, sub-radial thrust and scissors faults, as well
as folds extending radially from the center and concentrically encircling the
structure. The exterior portion of the structure exhibits extensional features: two
concentric, kilometer-scale folds, a monocline and syncline; and related small and
large scale normal faults which structurally thin formations within the syncline.
These faults are thought to link up with large scale faults in the transitional area,
forming blocks which converged upon the center during the deformational event.
Hypotheses formerly proposed for the structure’s origin include: a salt diapir; a salt
diapir formed over a basement uplift; a hydrotectonic pressure release conduit; a
buoyantly detached diapir; a cryptovolcanic feature; and a meteorite impact. Of
these, the salt tectonic and impact models are the currently favored hypotheses.
Though the detached salt diapir hypothesis adequately explains some of the features
of the structure, it fails to explain others. In fact, non-structurally detached diapirs
have never been observed in the field or the laboratory. The impact hypothesis is
able to explain many of the structures present, but similarly sized and eroded
craters have also never been found. Therefore, it is difficult to constrain Upheaval
Dome’s origin to any one hypothesis.

Table of Contents
Introduction ....................................................................................................................1
Local Lithologies & Paradox Basin History ..............................................................5
Pennsylvanian Deposits .............................................................................................5
Permian Deposits .......................................................................................................6
Triassic Deposits ........................................................................................................7
Triassic/Jurassic Deposits ..........................................................................................8
Types of deformation seen at Upheaval Dome ............................................................12
Deformation in the inner crater ..................................................................................12
Transition between inner and outer areas ..................................................................14
Deformation in the outer area ....................................................................................18
Presently available geophysical data .........................................................................19
Hypotheses for formation of Upheaval Dome .............................................................42
Hydrotectonic .............................................................................................................42
Cryptovolcanic ...........................................................................................................42
Simple salt dome ........................................................................................................43
Detached salt diapir....................................................................................................44
Meteorite (bolide) impact ..........................................................................................45
Discussion of Hypotheses in regard to Field Relationships ........................................53
Deformation in the inner “crater” ..............................................................................53
Transition between the inner and outer areas ............................................................55
Deformation in the outer area ....................................................................................59
Discussion........................................................................................................................62
Detached Diapir .........................................................................................................62
Impact Hypothesis .....................................................................................................65
Conclusions .....................................................................................................................67
Acknowledgments and Thanks .....................................................................................69
References .......................................................................................................................71

Geology and Structure of Upheaval Dome, San Juan
County, Utah: Salt or Impact Structure?
“The Upheaval dome [sic] is perhaps the most peculiar structural feature that has yet
been found… in southeastern Utah,” (McKnight, 1941, pg. 124).
“This baby ain’t no salt dome,” Eugene Shoemaker
(Siegal, 1993)
“[I]f the impact happened now, Moab would be buried by a significant amount of rock
and fried bighorn sheep” Jeff Plescia
(Siegal, 1995)
INTRODUCTION
Upheaval Dome is a structure consisting of a circular syncline approximately 5
km in diameter surrounding a complex, compressionally deformed and uplifted central
region 1.5 km in diameter (Figure 1). It lies within the sedimentary Triassic Moenkopi,
Chinle, Wingate, and the Jurassic Kayenta and Navajo Formations. Sedimentary
intrusives of the Permian White Rim Sandstone are concentrated in the extreme central
region. Upheaval Dome is located within the Paradox evaporite basin of the Colorado
Plateau, approximately 38 km southwest of Moab, Utah. A number of explanations for
its origin have been advanced: a salt diapir (McKnight, 1941; Fiero, 1958), a salt diapir
formed over a basement uplift (Joesting, Case and Plouff, 1958, 1966; Mattox, 1968
1975), a buoyantly detached salt diapir (Schultz-Ela, et al., 1994; Schultz-Ela, p.c.), a
cryptovolcanic feature (Butcher 1933, 1963 a,b), a hydrotectonic feature above a deep-
seated thrust fault (Kopf, 1982) and a meteorite impact (Boone and Albritton, 1938;
Dachille, 1968; Shoemaker and Herkenhoff, 1983, 1984; Shoemaker, Herkenhoff and
Gostin, 1993; Gustavson, et al., 1993). Of these explanations the salt tectonic and impact
models are currently favored.

Despite the controversy surrounding the origin of Upheaval Dome, very few
studies have been published on the structure. Fiero (1958) and Mattox (1968, 1975) did
the most extensive work on it; both support a fairly conventional salt tectonic mode of
origin. They propose a rising, but still buried, diapir as the cause for the structure. This
model is completely unable to account for the complexity of the structure, especially the
contractional structures found throughout the central region. Schultz-Ela (Schultz-Ela et
al., 1994; Schultz-Ela, p.c.) has proposed a more complex salt diapir model in which a
diapir rose through overlying sediments and became detached. He suggests that a
complex system of thrust faults formed behind the salt blob, closing behind it like a
camera iris. His model fits the structural character and complexity of Upheaval Dome.
However, Schultz-Ela's model seems quite unlikely. A buoyantly detached diapir similar
to the one he proposes has never been observed on the surface, though they do apparently
occur beneath some salt structures (Walters, 1993; Wu, et al., 1990).
The hydrotectonic model proposed by Kopf (1982) suggests the feature is a
pressure release pipe from a deep-seated thrust fault which is hypothesized to underlie the
entire Colorado Plateau. Kopf has attempted to use his model to explain various
enigmatic structures around the world, from Upheaval Dome to the Serpent’s Mound
structure in Ohio and the Vredefort Structure in South Africa. His hydrotectonic
hypothesis for these structures is preliminary, and not widely supported.
Bucher included Upheaval Dome in his 1933 list of cryptovolcanic structures in
the United States. It has since been recognized by other investigators (Dietz, 1963;
McCall, 1964) that so-called cryptovolcanic structures most likely resulted from
meteorite impact, rather than volcanic processes.
The impact model of origin is advocated in a limited number of abstracts (Boone
and Albritton, 1938; Dachille, 1968; Shoemaker and Herkenhoff, 1983, 1984;
Shoemaker, Herkenhoff and Gostin, 1993) and a preliminary paper produced by the
Carleton College Advanced Structural Seminar (Gustavson, et al, 1993).

Because of the complexity of the structure and the problems involved with
mapping it during the 1993 Advanced Structural Seminar, I continued work on Upheaval
Dome, in March of 1994 doing further mapping of the structure, and research on salt
tectonics and impact structures world-wide throughout 1994 and early 1995.
This paper will provide a necessary overview of Upheaval Dome and the work
that has so far been done on it, in preparation for the release of a paper by the Jet
Propulsion Laboratory, University of Nevada at Reno and California State University,
Domingez Hills. The paper begins with an introduction to the sedimentary units present
at and under Upheaval Dome, then moves on to describe the deformation present at the
dome. It then discusses the structures predicted by the hypotheses so far proposed for the
formation of the structure, interprets the hypotheses in terms of these structures and then
critiques the hypotheses.

Figure 1. Oblique air photo looking west across Upheaval Dome, with
north to the right. Notice the concentric rings of the structure, and the
breach in the west wall. Photo from Shelton’s Earth Science slides.

LOCAL LITHOLOGIES & PARADOX BASIN HISTORY
Upheaval Dome lies in the Paradox Basin (see Figure 2), an area known
geologically both for the salt anticlines that formed in the deeper parts of the basin there
and for the colorful Triassic and Jurassic sedimentary rocks that later filled it.
The Paradox Basin was first formed around 1,700 Ma when “tectonism dissected
the basement into rhomboidal blocks jostled among northwest- and northeast-trending
wrench faults… The northwest-southeast set of basement faults were the dominant trend
in the east Colorado Plateau region” (Baars, D.L., 1966, from Baars, 1987). This
basement fabric was re-activated in the Middle Pennsylvanian, perhaps through an
intercontinental plate collision (Kluth and Coney, 1981, from Baars, 1987). Sinistral
strike-slip and thrust faulting produced the Paradox Basin and the Uncompahgre Uplift
(the southernmost segment of the Ancestral Rockies) (Hintze, 1988), and influenced the
paleo-geometry of the entire area.
Arkosic sediment was deposited in the basin, transported from the higher
Uncompahgre Uplift to the east. Later, Pennsylvanian evaporites were deposited in
“paleotectonic grabens and half-grabens of the deeper basin” (Baars, 1987). These
grabens and half-grabens later influenced the flows of salt into the anticlines in the
eastern part of the basin.
Pennsylvanian Deposits
The initial Pennsylvanian sedimentary units believed to have been deposited on
the Precambrian basement surface are a thin group of muddy shales, not more than 200
meters thick (Baars, 1987).
Above this formation is the Paradox Formation, a thick sequence of interbedded
evaporite salts and black shales. There are at least 29 black shale beds within the
Paradox evaporites, some have even been named and are used to correlate oil wells with
oil producing horizons. The Paradox is up to 1000 meters thick in some areas of the

Paradox Basin, and has deformed to thicknesses of up to 2000 meters in the areas where
salt has moved to form the salt anticlines. In a well approximately 20 km northeast of
Upheaval Dome, the Paradox is 1000 meters thick, with at least 20 shale interbeds
(Plescia, et al. 1993), while the Husky Oil Company, Buck Mesa 1 well within the rim
syncline surrounding Upheaval Dome shows the Paradox is 450 meters thick, with 15
shale interbeds. Near Moab, the evaporites from the Paradox Formation are being mined
for their potash fraction for use as fertilizer; elsewhere, the salt anticlines have trapped oil
and gas along their flanks and seem to have concentrated the uranium mineralization that
occurred on the Colorado Plateau in the Late Tertiary and the Eocene (Shoemaker, 1955).
Following the Paradox Evaporites, the Hermosa Group, comprising the
Desmoinesian and Missourian Honaker Trail Formation and the Elephant Canyon
Formation, was deposited. These formations are normal marine carbonate and related
clastic deposits with fossils that include fusulinids (Baars, 1987). These Pennsylvanian
deposits are not exposed at Upheaval Dome, thought they underlie the structure and may
play some part in the formation of the structure.
Permian Deposits
The Permian history of the area is represented by the mostly reddish-brown,
noticeably arkosic, largely fluvial, sandstones, siltstones and mudstones of the Cutler
Formation (Baars, 1987). A medium- to fine-grained sandstone, presumably the Permian
White Rim member of the Cutler Formation, crops out as sedimentary intrusive dikes and
sills in Upheaval Dome. Throughout the rest of this paper, it will be assumed that these
sedimentary intrusives are in fact the White Rim, since this is how they have been
described by Fiero (1958) and Shoemaker and Herkenhoff (1983, 1984). The White Rim
is the uppermost Permian unit in Canyonlands and forms distinctive white ledges in the
bottomlands of Canyonlands National Park. The White Rim pinches out beneath Dead
Horse Point State Park northeast of Upheaval Dome and thickens to 150 meters toward

the Green River (Huntoon, et al., 1982). It is a white, very fined-grained, arkosic
sandstone, which grades westward into the Toroweap Formation. Some authors believe
that it is an eolian deposit (Baker, 1946), while others believe that it is a marine sandstone
(Baars & Seager, 1970; Chan and Huntoon, 1984)
There is probably a significant unconformity between the Permian and Triassic
beds in Canyonlands; however, its location is unsure. It is possible that it lies within the
Moenkopi, as in places Moenkopi are erosionally truncated within the red-bed sequence
several meters above the White Rim surface (Baars, 1987).
Triassic Deposits
The Moenkopi Formation is considered to be Early and Middle Triassic. It
unconformably overlies Permian or older rocks and the Pennsylvanian evaporites along
salt anticline crests, indicating that the salt began to move before and during the Triassic.
Near and within Upheaval Dome, the Moenkopi is reddish-brown to greenish-gray, but
elsewhere in Canyonlands it is uniformly reddish-brown. The Moenkopi is a micaceous,
thinly laminated siltstone and sandy siltstone. The sandstones are very fine-grained and
crossbedded, with remnant ripple marks and minor gypsum. It is interpreted as a low-
energy marginal marine deposit that grades from a tidal flat in the east to shallow marine
facies in the west (Molenaar, 1987). Elsewhere in Canyonlands, it is 160 meters thick
(Fiero, 1958); however, within Upheaval Dome, the deformation is too extensive for an
accurate thickness determination.
The Triassic Chinle Formation lies above the Moenkopi and is divided into three
distinct members, the Mossback, Black Ledge and Church Rock. The basal Mossback
Member (thought to be correlative with the Shinarump Conglomerate exposed elsewhere
in Canyonlands) is a ledge-forming conglomerate consisting of yellowish gray fine- to
medium-grained sandstone matrix, containing chert pebbles and silicified wood

fragments (Fiero, 1958). It is 2-20 meters thick in Canyonlands; within Upheaval Dome,
it is between 2 and 5 meters thick.
Lying conformably above the Mossback is the Church Rock Member of the
Chinle. The Church Rock is a greenish-gray and red mottled, bentonitic shale of fluvial
and lacustrine origin. For mapping purposes, the Church Rock was divided into two
sections, the Lower Church Rock and the Upper Church Rock. The Church Rock is
approximately 105 meters thick. The Black Ledge Member of the Church Rock lies
approximately 35 meters above the Mossback member, and separates the Church Rock
into the Upper Church Rock and the Lower Church Rock (see Figure 3).
The Black Ledge is a gray limestone conglomerate with varied sandstone and
limestone clasts. It is distinctive in that it weathers to an jagged black ledge. It is 10
meters thick at Upheaval Dome. The total thickness of the Chinle is 110 meters (Fiero,
1958; Mattox, 1968, 1975).
Triassic/Jurassic Deposits
The Glen Canyon Group (Wingate, Kayenta and Navajo) overlies the Chinle
Formation. It is of uncertain age; some authors consider the Wingate and Kayenta to be
Late Triassic (Lewis, et al., 1961, Galton, 1971), others believe that they were deposited
in the Early Jurassic (Hintze, 1988). The actually Triassic/Jurassic boundary probably
lies somewhere within the Glen Canyon group.
The Wingate Formation is a massive, cliff-forming unit, pale orange to light-
brown in color, well-sorted, very fine- to fine-grained, cross-bedded, eolian, arkosic
sandstone. It is 64 meters thick at Alcove Spring and has large (5 to 15 meters) scale
cross beds, which are hidden by prolific brown desert varnish. The eolian crossbeds dip
predominately to the southeast, indicating a paleo wind direction from the northwest
(Fiero, 1958).

The Kayenta Formation conformably overlies the Wingate. Its thinly- to
massively-bedded sandstones are separated by thin shale layers and lenses, and a number
of limestone- and limey-sandstone beds. The total thickness of the Kayenta is 80 meters.
The sandstone has some small scale (25 to 50 cm) cross bedding, with beds ranging in
thickness from 10 cm to 5 meters. The sandstones are very fine- to medium grained,
colored red, white or gray, while the shales and mudstones tend to be red and gray (Fiero,
1958). The Kayenta is thought to be a fresh-water braided fluvial deposit, whose
sediment was probably from the Uncompahgre Uplift to the east and northeast (Dubiel,
1989). The contact between the Kayenta and the Wingate is chosen to be the first
significant green/red/gray shale layer above the massive Wingate sandstone beds.
The Navajo/Kayenta contact is also conformable. The Navajo (called the Nugget
in Colorado, Wyoming and northern Utah) is a white-yellow-buff, eolian sandstone, with
massive crossbedding that weathers brown to buff. It crops out in a wide belt of rounded
cliffs and “picturesque” domes (Molenaar, 1987). The foresets of the crossbeds dip
dominantly to the southeast, indicating a paleo wind direction from the northwest. The
top of the Navajo contains some thin limestone beds which have been interpreted as
playas. The Navajo probably represents deposition in an interior desert, with the
oceanic shoreline far from the present edge of the Colorado Plateau. The total thickness
of the Navajo is unknown in the Upheaval Dome area due to the erosion which has
removed its upper contact, but it is up to 150 meters thick elsewhere in Canyonlands
National Park (Molenaar, 1987).
Middle Jurassic (the San Rafael Group) and thick Cretaceous sediments covered
the area at some time in the past, but have since eroded. The thickness and even the
presence of these deposits is unknown during the deformation of Upheaval Dome. The
nearest outcrops of the Middle Jurassic San Rafael Group; the Page Sandstone, an eolian
unit derived from and resembling the Navajo; the Carmel Formation, a greenish-gray and
red silty shale; and the Entrada Sandstone, a light-buff to light reddish-brown or salmon

colored, very-fine to fine-grained sandstone (Molenaar, 1987) are 35 km north east of
Upheaval Dome (McKnight, 1941) along Utah State Highway 313. The nearest deposits
of the Cretaceous units are those in the Book Cliffs region along Interstate I-80, 100 km
north of Upheaval Dome. At their maximum, the Cretaceous deposits probably exceeded
1300 meters in thickness over the Upheaval Dome area (Hintze, 1988).

Figure 2. Index map showing the location of Upheaval Dome and salt anticline in the
Paradox Basin, as well as a key to the kilometer square location identifiers discussed in
text.

Figure 3. Stratigraphic section for Upheaval Dome. Unless otherwise noted, taken from
Fiero (1958), after Gustavson et al. (1993).

TYPES OF DEFORMATION SEEN AT UPHEAVAL DOME
There are three different deformational regimes at Upheaval Dome. The interior
crater, a circular area with a diameter of 1 km, exhibits extreme contraction/constriction,
with thrust faults and tight to open folds doubling and in places tripling the Triassic
Moenkopi. This area will hereafter be referred to as the central compressional zone.
Outside of this zone, extending from about 500 meters to 1.5 km from the center of the
structure, is an area of moderate compression, characterized by mesoscale (small scale)
faulting, radially and concentrically oriented folds as well as kilometer scale rotating
thrust faults. This zone extends to the hinge of the rim syncline, and will be referred to as
the transitional area. Its deformation decreases in severity with increased distance from
the center. In the exterior, from the rim syncline hinge to the flat-lying units, lies a zone
of extension, where structures such as low angle normal faults, grabens and a gentle
concentrically oriented syncline and monocline occur. This will be referred to as the
exterior extensional area.
Deformation in the inner crater
The inner crater is characterized by a very complex, contractional regime,
generally characterized by thrust and high angle reverse faults (see the geologic map on
Plate 1). Often times these faults terminate in tight toe folds, as seen in Figure 4. Many
other types of folds are represented in the interior: open folds, with a small amplitude and
long wavelength (Figure 5); White Rim intruded folds; as well as broken and faulted
folds. Fault plane orientations are often difficult to measure, but faults are obvious from
a distance because of marker unit (say the Mossback Member of the Chinle Formation)
duplication. There are so many impressive, overlapping structures in the interior that the
job of mapping is often overwhelming. Displacement and sense of motion along these
faults is often impossible to discern, due to the weathered nature of the Moenkopi shale,
and the general jumbledness of the center. It is estimated that thrust fault displacements

may involve more than 200+ meters of movement. These faults lie in a sub-radial
pattern, and are characterized by Schultz-Ela as similar to the diaphragm plates of a
camera iris.
Despite its complex deformation, sandstone beds within the Moenkopi in the
center are amazingly well preserved. These beds are generally coherent, and primary
sedimentary structures such as ripple marks have been preserved, as in Figure 6. The
Moenkopi might be considered brecciated on a much larger (100+ m) scale, but beds are
clearly not brecciated on an outcrop scale. Shoemaker found what he believes is a
shatter cone in a very fine-grained sandstone bed of the Moenkopi (Figures 8 and 9)
(Herkenhoff, p.c.).
The Permian White Rim Sandstone exploits central fault zones and other areas of
weakness to intrude into the central crater. White Rim intrusives are more resistant to
weathering than surrounding Moenkopi, and therefore tend to form towering spires in the
central region. The White Rim intruded upward into the dome from approximately 200
meters below the present tips of the central spires (see Figure 3 for a stratigraphic
section). The White Rim shows signs of intruding upward: unconformable contacts,
enclosed fragments of the Chinle or Moenkopi within the White Rim (Figure 10), drag
folds where intruding White Rim has dragged the surrounding Moenkopi upward
(Figures 11a and 11b), fingers which infiltrate fractures in folds, intrusion along bedding
planes that are now vertical (Figure 7), and intrusion between the Chinle and Wingate
contact (Figures 11a and 11b).
The basal Mossback Member of the Chinle formation crops out extensively
throughout the central crater. It contains fossilized organic matter, generally limonized
tree trunks. In places within the dome, these tree trunks have been heat metamorphosed
to anthracite (Giegengack , p.c.). It also contains trace amounts of apatite which are
currently being analyzed at the University of Pennsylvania. These apatite crystals
contain minor quantities of radioactive elements within the crystal lattice, which form

fission-tracks as they decay. These fission-tracks are relatively easy to reset at a
moderate temperature through heat annealing (Giegengack, p.c.), and therefore allow the
age and magnitude of a heating episode to be determined. A preliminary study at showed
that these fission tracks were in fact reset (Giegengack, p.c.). Giegengack hopes to use
this fission-track dating technique on 150+ kg of Mossback taken from the dome in
January, 1995 to determine if and when a heating event occurred.
The amount of deformation in the Moenkopi decreases with distance from the
center. This can be seen in the stream courses which exit the dome through Upheaval
Canyon. In the very center (A1) (Figure 4) the deformation is intense, while further out
(C16) (Figures 12a and 12b) the Moenkopi is nearly flat-lying, with a few, relatively
small displacement, faults.
Gustavson et al. (1993) found two grains of shocked quartz within the White Rim
intrusions, from a population of 10 samples thin sectioned. These grains displayed two
sets of shock features, oriented in the ω and π directions, the typical orientation of planar
deformation features (Alexopoiulos, et al., 1988). However, the scale and quality of this
study were limited.
Transition between inner and outer areas
In the transitional regime, which reaches from about .5 km to 1.5 km from the
center, a number of specific types of deformation, both brittle and ductile, occur.
Perhaps the most impressive structure of this transition regime is a concentrically
oriented tightly-isoclinal, slightly-overturned syncline (TISOS ) first mapped by the 1993
advanced Structural Seminar (see Figure 13b). This fold can be seen in Figure 13a,
where the beds are seen dipping into the central crater (to the right) and then arching up
and over themselves. The TISOS crops out fully in only one place (on the east side, SE
1/4 of NW 1/4 B4), but it is hypothesized to have encircled the entire central crater region
before erosion. It is deformed by the nearly perpendicularly oriented radial folds,

creating an irregular, concentrically oriented fold axis. The TISOS can be observed in
three other locations. It can be seen in the dogs tongues, narrow tongues of Wingate
which dip steeply into the center. These dogs tongues crop out in the northeast corner of
the central crater (SW 1/4 of SW 1/4 B3), on the west side of the crater (NE 1/4 of SE 1/4
B8) and the southeast corner of the central crater (SE 1/4 of SE 1/4 B8). From a distance
(Figure 14) it is obvious that these dogs tongues exhibit the effects of the TISOS as they
plunge into the central crater and then turn up at their ends.
A large amplitude, concentrically oriented anticline surrounds the crater just
outside the TISOS (see Plate 1). The inner limb of this anticline forms the outer limb of
the TISOS. This concentrically oriented anticline uplifts the Wingate in portions of the
north, south and east sides, and probably continued around the dome before it was
eroded. This anticline stands out well on the stereographic airphotos as a high point
where the Wingate is uplifted above its stratigraphic level in the rim syncline. The limbs
of this fold change in orientation as the height above the base of the Wingate changes; the
limbs in the basal portion of the Wingate form isoclinal folds (Figure 16), while the upper
portions of the Wingate form folds with a more open character.
Another set of impressive structures are large-scale, ramping thrust faults in the
Glen Canyon Group, which extend from just outside the rim syncline to the inner
transitional area. In the exterior, they outcrop as low angle normal faults, often times
dramatically thinning the Wingate. In the transitional area they crop out as ramping
thrust faults with a good deal of scissors motion and are often hidden in the Kayenta. In
fact, these faults are most clearly located by studying air photos and observing changes in
the orientation and severity of deformation of the Wingate, Kayenta and Navajo that
occur in bands around Upheaval Dome (see Figure 1). For example, the band of
Kayenta/Navajo in the eastern transitional area is wide, relatively flat-lying and
undeformed (see Plate 2), while the band of Kayenta in the northern and southern
transitional areas is narrower, much steeper and far more complexly deformed (see Plate

2). These bands represent blocks which are separated by the large-scale ramping thrust
faults.
It is difficult to connect these inner contractional faults with the exterior tensional
faults because of their extremely large scale; however, such a connection is proposed
because of the excellent view of such a fault along the syncline loop trail in Syncline
Valley (see Plate 1, C16, C1, C2, C3 and B2; Plate 2). I believe that there could be
several of these faults which thrust Glen Canyon Group blocks from outside the rim
syncline into the center, creating the topographically high rim around the crater.
Especially in the southern and northern bands of the transitional regime, the
Kayenta displays another kind of transitional deformation: it is extensively crumpled an a
complex, often chaotic, three dimensional manner. Steeply dipping beds are common,
and beds thicken, thin and fracture from intense constriction (see Figures 17 and 18).
Despite the internal crumpling of the Kayenta, its general trend follows the folding of the
underlying Wingate, often creating parasitic folds over major structures in the underlying
Wingate.
Another important component of deformation throughout the transitional area is
the radial folding found in the Wingate, Kayenta and Navajo. At the base of the northern
Wingate crater wall, there are 6 fairly tight radial anticlines, visible in the uppermost
Chinle (Figure 16). These folds are akin to what is seen on the surface of a cloth
enclosing a ball with a rubber band at its base when it is laid ball-up on a table (see
Figure 19). They have an amplitude of 10 to 15 meters, and are generally 25 to 30 meters
wide. The uppermost Chinle bed in one of these tight radial anticlines is broken (see
Figures 20a and 20b), with the limbs of the fold sloping away from the broken axis at
about 30°. The radial folds are also prominent in the overlying Kayenta and Navajo (see
Plate 1), though their character changes significantly in these formations.
In the outer transitional area there are many smaller thrust faults which help ramp
the Wingate, Kayenta and Navajo to high elevations, as observed in the stream valley

wall (Figures 21a and 21b), and in the Navajo island on the west side of the dome (see
Plate 1).
Mesoscale faulting is pervasive within the Wingate, Kayenta and Navajo
throughout the transitional regime. The number of faults per unit volume is quite high
close to the center, and fault density decreases towards the exterior. These mesoscale
faults extend over 1 cm to 1 meter, with a displacement of a fraction of a millimeter to 1
or 2 cm (Figure 22). The strike of the fault surfaces is difficult to discern because of the
rounded outcrop character of the Wingate, Kayenta and Navajo; however, they generally
mirror the orientation of surrounding structures.
The greatest difficulties in studying the transitional regime are due to the outcrop
character of the Wingate. The Wingate is a massive, eolian sandstone, the most
prominent cliff forming unit in Canyonlands, is covered with desert varnish, and full of
huge crossbeds. This makes it very difficult to discern beds and faults within it (look
above the Chinle anticlines in Figure 16). However, in places it is obvious that important
structures are hidden within the Wingate. Two such places are shown in Figure 23 (NE
1/4 of SE 1/4 B2) and in Figure 24. In Figure 23, an apparent bed in the Wingate pinches
out above a Chinle-cored anticline at the base of the Wingate cliff (Schultz-Ela, p.c.).
Schultz-Ela believes that this represents a growth fold, formed as this anticline was raised
above the erosional surface during deposition. In Figure 24, a shale bed of the lower
Wingate is intensely deformed, with little visible deformation in the surrounding
Wingate. These are examples of important structures in the Wingate which are masked
by the weathering character of the Wingate.
Generally, structures in the transitional area indicate that outer rocked moved
inward during the deformational event. This movement appears to have occurred over a
very short time as seen by the broken Chinle anticline in Figure 20. The contractional
deformation extended far out from the crater walls, and used methods similar to the

camera-diaphragm like deformation of the central area to accommodate the
circumferential shortening.
Deformation in the outer area
Deformation in the outer area is dominated by the large, concentrically oriented,
rim syncline which completely encircles the dome (see Plate 1). A wider monocline
surrounding the rim syncline drops the relatively flat-lying beds 230 meters into the axis
of the syncline. The beds then climb 380 meters through the transitional area, cresting at
the crater’s rim, 150 meters above the surrounding stratigraphic elevation (see Figure 25)
(McKnight, 1941, plate 3).
Generally, the other structures in the outer area are superimposed upon and follow
the trend of the rim syncline. They are primarily large scale tensional faults. Many of
these are low angle normal faults within the axis of the syncline which dramatically thin,
and in places remove, the Wingate. Portions of these structures are visible in the cliff
walls on the south side of Upheaval Canyon and east of Holeman Spring (Figures 12 and
27). Similar faults are mapped by Schultz-Ela in the alcoves north of Alcove Spring
(Schultz-Ela, p.c.). As described in the previous section, some of these faults may
connect with major thrust faults in the transitional area.
Tensional features also occur beyond the axis of the rim syncline. This is well
represented by the presence of a normal graben found south-southeast (SE 1/4 of NW 1/4
C9) of Alcove Spring (see Plate 1). This graben, with a point-to-point displacement of
about 120 meters on the northern fault and 20 meters on the southern fault, occurs in the
Navajo and Kayenta formations. The faults converge in the lower Kayenta. Abrasive
groove slickensides (i.e. not mineral alignment slickensides) (Figure 27) were found on
the southern fault, and beds within the Kayenta are dragged by the displacement (Figure
28) of the fault. A branching of the normal fault occurs, creating a second fault and a
series of smaller en echelon and conjugate normal faults (Figure 29).

The outer structures support the theory that the exterior portions of the structure
converged upon the center. They were able to accommodate the extensional stress of
convergence through normal faulting parallel to the axis of the syncline. This convergent
movement caused the circumferential shortening of the inner and transitional regimes.
Presently available geophysical data
The geophysical data presently available for Upheaval Dome and the surrounding
area are complex and not well understood. Both aeromagnetic and gravity data show
pronounced anomalies at Upheaval Dome. The magnetic map shows a pronounced high
over Upheaval Dome and the adjacent Gray’s Pasture. The gravity data display a broad
high over most of the structure with a 2 milligal inversion (low) directly on top of it
(Joesting and Case, 1958; Joesting, et al, 1966).
The use of gravity and magnetic data in the study of impact structures can be both
powerful and ambiguous. Some structures show gravity highs and magnetic lows, others
show magnetic lows and gravity highs, others show no anomalies (Plescia, p.c.). Only
occasionally do the geophysical data prove an impact origin for a structure; it is usually
just part of the puzzle.
The JPL seismic study of Upheaval Dome in January, 1995 collected gravity data
at more than 40 stations within and surrounding the structure. This study, when
processed, should supply a stronger idea of the gravity picture at Upheaval Dome1.
1 As of August 28, 1995, some preliminary findings of this study can be found on the World Wide
Web at http://www.seismo.unr.edu/ftp/pub/louie/dome/refraction.html.

Figure 4. Numerous thrust faults and
related folds intersect at Turret Rock,
located in the central crater. This structure
indicates the complex compressional
regime that existed during the formation of
Upheaval Dome.

Figure 5. Sweeping folds like these occur throughout the central crater.
In this picture, you can also see a fault in the distance, where the beds
which occur in the foreground terminate against beds with a perpendicular
orientation.
Figure 6. These Moenkopi beds display original sedimentary structures,
and have not been brecciated. They do, however, dip at approximately
70° to the west (photo looking east).

Figure 7. The Permian White Rim sandstone (the whiteish, somewhat
planar dikes on the tops of the reddish, bedded Moenkopi) intrudes along
vertical Moenkopi bedding planes in the central crater. This photo was
taken from the top of the east Wingate wall.
Figure 8. Shatter cone found by Shoemaker in a fine-grained sandstone
bed of the Moenkopi in the central crater. This is a pretty poor example of
a shatter cone, ideally, the striations on the edges would be stronger, a
point would be preserved and other shatter cones would interlock with this
one in a cone-in-cone structure. Centimeter scale along the bottom. Photo
provided by Ken Herkenhoff.

Figure 10. These rounded inclusions of
Chinle shale are found in an intruded
segment of White Rim high up in the
Chinle near the Wingate wall (NW 1/4 of
the SW 1/4 B4). They show that the White
Rim did penetrate the Chinle during the
deformational event.

Figure 11a. These drag beds were formed the White Rim intruded
upward from below.
Figure 11b. Tracing of Figure 11a, showing the White Rim/Chinle
contact and the drag fold formed within the Chinle.

Fig
ure 12a. The axis of the rim syncline, seen to the south of Upheaval
Canyon (the breach in the west wall of the dome). Though difficult to see,
the Wingate is structurally thinned along a low angle normal fault. Note
the graben preserved in the colorful beds of the Upper Moenkopi in the
lower foreground.
Figure 12b. A tracing of the above photograph, showing the location of
the low angle normal fault and the demarcation of the various units. TRn
= Navajo; TRk = Kayenta; TRw = Wingate; TRc = Chinle; TRm =
Moenkopi.

Figure 13a The tightly isoclinal, slightly overturned syncline (TISOS), as
seen from the Upheaval Dome overlook on the south side of the dome.
Note that the beds dip into the dome, then turn upward and terminate in
the air.
Figure 13b. Schematic cross section of the east side wall of Upheaval
Dome. Note that the TISOS does not exist as pictured here, but rather as a
number of slightly overturned beds rising into the air as seen in Figure
13a.

Figure 14. One of the dogs tongues which outcrop around the crater.
This one, in the northeast corner shows their typical characteristics; a
plunge into the center and then a flip up at the end. These dogs tongues
apparently represent the remains of the TISOS in the Wingate.

Figure 15a. This picture is of a concentrically oriented anticline just
outside of the hypothesized location of the TISOS on the east side of the
crater. It shows the tight anticline which presumably encircled the dome
outside of the TISOS.
Figure 15b. Tracing of Figure 15a detailing the concentrically oriented
anticline on the west side of the dome.

Figure 16. A photo of the north wall of the crater, from the overlook in
the south. The radial anticlines at the base of the Wingate cliff are the
expression of the constriction that occurred as the Wingate moved inward
during the deformational event.
Figure 17. The general crumpled nature of the Kayenta south of the
dome, between the crater wall and the parking lot. The beds in the
foreground are deformed into a syncline, the beds in the middle ground are
flat, but dipping to the south, while the beds in the pinnacle in the far
middle ground are vertical.

Figure 18. An enlarged portion of Plate 1, showing the extreme amount and tightness of
the deformation in the south-east corner of the transitional regime.
Figure 19. The radial anticlines that result from constrictional shortening are shown
here, with a tennis ball wrapped in cloth. The grid scale is 5 cm.

Figure 20a. This Chinle radial anticline is found on the west wall of the
crater. Note the broken upper beds, and the Wingate filling in the fracture
from the top.
Figure 20b. A tracing of Figure 20a showing the broken upper Chinle
beds.

Figure 21a. The north wall of Upheaval Canyon, in the S 1/2 of section
B1. Note the thrust faults offsetting the lowermost Kayenta beds at the top
of the Wingate cliff, and the difficulty in following these thrust faults
through the Wingate.
Figure 21b. A tracing of Figure 21a, showing the location and sense of
motion on the thrust faults in the upper Wingate wall.

Figure 22. An example of the mesoscale faults found throughout the
transitional regime. These mesoscale faults have offsets between .01 mm
and 5 cm, and are present in the greatest quantities close to the dome.

Figure 23. The growth fold in the Wingate above a radial Chinle anticline
in the north-east corner wall of the crater used by Schultz-Ela as an
indicator of slow, episodic deformation. Photo courtesy of Dan Schultz-
Ela, University of Texas at Austin Bureau of Economic Geology.

Figure 24. This shale bed is exposed in the lower Wingate in the north
wall of Upheaval Canyon, just below the thrust faults seen in Figures 21a
and 21b. The shale bed has been shortened to 50% of its original length.

Figure 25. Looking west, across the dome at the difference in
stratigraphic level between the formations at the dome and their regional
elevations.
Figure 26. This oblique view shows one of the low angle normal faults in
the Wingate wall east of Holeman Spring.

Figure 27. These abrasive slickensides are found on the Navajo hanging
wall along the south fault of the graben in the syncline, indicating that
both the Kayenta and Navajo were lithified at the time of deformation.
Figure 28. These Kayenta beds were dragged downward along the
footwall of north fault of the graben in the syncline.

Figure 29. These en echelon faults formed in the hanging wall of the
normal graben in the rim syncline when the fault split into two separate
fault planes.

HYPOTHESES FOR FORMATION OF UPHEAVAL DOME
The multitude of hypotheses on the formation of Upheaval Dome are described in
the following section. In the next section, Discussion of Field Relationships and
Hypotheses, the valid hypotheses are analyzed in relation to the features found at
Upheaval Dome (described in the preceding section, Types of deformation seen at
Upheaval Dome).
Hydrotectonic
Rudy Kopf, formerly of the USGS, believes that Upheaval Dome is the release
pipe for a hydrotectonic bellows, located along an extremely deep, low angle thrust fault
which pumps fault slurry out through Upheaval Dome at irregular intervals. He believes
that this hydrotectonic bellows is powered by a non-planer fault below the water table
whose “wavy wallrock surfaces form chambers and bottlenecks along the fault.” Fluid
fills these chambers and bottlenecks, and the interaction of the hanging wall and foot wall
form a “powerful subsurface reciprocating pump,” which compresses water along the
fault plane, forcing it to exploit any weaknesses in the overlying rocks (Kopf, 1982).
This hypothesis is extremely hypothetical and is not widely accepted by the investigators
studying Upheaval Dome (Schultz-Ela, p.c.; Plescia, p.c.; Herkenhoff, p.c.).
Cryptovolcanic
One of the original hypotheses for the formation of Upheaval Dome (Bucher,
1933) is that it was formed by a cryptovolcanic event. Many of the structures identified
by Bucher (1933) as cryptovolcanic structures have, in recent years, been reclassified as
bolide impacts (Dietz, 1964). Since the local igneous intrusions (large scale laccolithic
intrusions) are not associated with cryptovolcanic events, and there are no volcanics
preserved within Upheaval Dome, the cryptovolcanic hypothesis can be discarded. Thus,
while fitting some of the characteristics of a cryptovolcanic structure, Upheaval Dome is

no longer considered one by most investigators (Mattox, 1968, 1975; Shoemaker and
Herkenhoff, 1984; Schultz-Ela, 1994).
Simple salt dome
The Pennsylvanian evaporite deposits which underlie Upheaval Dome and the
proximity of the salt anticlines elsewhere in the Paradox basin encouraged previous
investigators to propose a salt tectonic origin for Upheaval Dome (McKnight, 1941;
Fiero, 1958; Joesting and Case, 1960; Joesting et al., 1966; Mattox, 1968, 1975; Schultz-
Ela et al., 1994; Schultz-Ela, p.c.). Jackson et al. (1994) provide an excellent
introduction to salt tectonic theory:
“The structural dynamics of salt systems—salt tectonics—encompasses
any deformation involving salt or other evaporites. It includes halokinesis,
in which deformation is driven primarily by salt upwelling and
withdrawal, not by regional tectonics. A salt-tectonic system is composed
of a source layer of rock salt or other evaporites (collectively referred to as
“salt”), overlain by sedimentary overburden, and overlying a basement of
the sub-salt strata.”
The simple salt dome theory supports a rising, but still buried diapir as the cause
for the structural deformation seen at Upheaval Dome (McKnight, 1941; Fiero, 1958;
Joesting and Case, 1960; Joesting et al., 1966; Mattox, 1968, 1975). Such diapirism
occurs only under certain conditions. Firstly, the rising material must be less dense than
the overlying sediment, or the source layer must be differentially loaded. Secondly, there
must be overburden pressure to initiate buoyant rising of the salt mass. Thirdly, the
diapir material must have an ‘escape’ route through the overburden. In order to initiate
buoyant rising of the salt mass, there must be a lateral pressure differential so that the
rising potential of the salt is concentrated into one area.
As the salt diapir begins to form a bulge in the parent salt layer, it will deform the
overlying beds into a dome shape directly above the rising salt mass. As seen in Figure
30, extensional structures, generally normal faults, are found in the sediments directly

overlying the diapir (Jenyon, 1986). Additionally, salt from around the salt swell will
migrate inwards towards the rising mass. Because of the removal of this salt, the
overburden will subside around the bulge in the salt to form a circular syncline, called the
primary rim syncline. If the salt mass continues to rise, it may pierce the overlying rock
layers, and salt from the mother layer will continue to flow laterally to feed the rising
diapir. This rapid removal of salt from the edges of the salt diapir frequently creates
secondary extensional structures around the diapir, including circular and radial normal
faulting (Jenyon, 1986).
However, none of the extensional structures expected over the rising diapir are
present at Upheaval Dome. Since these are an integral part of the expected structural
regime, the rising diapir model can be discarded.
Detached salt diapir
Members of a research team from the University of Texas at Austin Bureau of
Economic Geology, led by Dr. Martin Jackson, recently proposed a different salt tectonic
theory for the formation of Upheaval Dome. The group, working with the Exxon Field
School advanced a hypothesis whereby a salt diapir was initiated early in the history of
the structure. It buoyantly rose and passed through the area, becoming detached from the
mother salt layer at some time. They believe that salt movement may have begun in the
Middle Pennsylvanian during deposition of the Hermosa Group as a simple salt diapir
(note thickening in the Hermosa in Figure 31) and continued episodicaly, with times of
movement interspersed with long hiatuses. This left some units thickened in the rim
syncline, while others are unaffected by the early deformation. They hypothesize that at a
later time, perhaps due to depletion of the source layer or increased sediment load, the
salt diapir became detached from the source layer as the rocks surrounding the feed stock
converged beneath the salt blob like a camera iris (see the Pinch-Off Stage plan view in
Figure 32) (Schultz-Ela, p.c.).

The detached diapir hypothesis predicts different deformational regimes in
different areas, much as seen at Upheaval Dome. In the interior, Schultz-Ela et al. expect
to see an intensely constrictional regime, with much shortening through thrust faults and
folds, which occurred after the salt blob passed through the area. This would have been
caused as the surrounding formations constricted to fill the space left by the departing
salt. This shortening continued through the transitional regime but was less intense,
since, as the circumference increases, the shortening per unit area decreases. In the
exterior of a detached salt structure, Shultz-Ela et al. expect extensional structures which
resulted from the movement of the formations towards the center after the salt passed
through.
Meteorite (bolide) impact
Another hypothesis for the formation of Upheaval Dome that has gained favor in
recent years, and has been published in the mainstream press (Siegal, 1993, 1995; The
Associated Press, 1993; Huntoon 1986) is that the structure is a deeply eroded crater of a
midsized (~500 meter diameter) bolide impact. Shoemaker and Herkenhoff (1983, 1984)
believe that this bolide impacted at Upheaval Dome and created a small, complex crater
(see Figure 33). Bolides moving at more than a few km/sec, impacting sedimentary
surfaces, form simple craters like Meteor Crater if they are less than 50 meters in
diameter. Impactors larger than 50 meters tend to create multi-ring, complex craters with
a central uplift (Melosh, 1989).
The structures expected deep beneath a midsized impact crater in a sedimentary
target have never been observed in the field — there are no impact craters on Earth of
that size in sedimentary rocks that are eroded and exposed. Dence, et al. expect a central
uplifted area deep beneath a midsized crater greater than 3 km in diameter (1977). This
uplifted area would be weaker than the surrounding rocks and could allow sedimentary
units like the White Rim to intrude upward. Shock metamorphism is expected in the near

surface units directly under the crater. Also, as the central portions of the structure were
uplifted, the surrounding formations would converge on the center, causing constrictional
features like radial folds, concentrically-oriented folds and small scale faulting in the
massive sandstone formations.
In the outer portions of the structure, large scale extensional features are expected.
These are found in the Red Wing Creek structure in North Dakota. The discovery of oil
at the Red Wing Creek structure in 1972 encouraged extensive well drilling and seismic
work there to discover the nature of the sub-surface oil traps. This work showed a buried
circular structure 8 km in diameter with a central uplift and surrounding ring depression
(Brennan et al., 1975). Brennan et al. hypothesized that the structure was due to a
Jurassic impact at the site which was quickly covered with Middle Jurassic sediments.
This rapid burial caused oil and gas to be trapped within the structure. Other than Red
Wing Creek, few impact structures of this size in sedimentary rock have been studied
with seismic techniques, therefore these seismic line are only available data to compare
with deep, sub-crater deformation that is possibly expressed by Upheaval Dome. Since
the Red Wing Creek structure is buried under a 600 meter thick blanket of post Jurassic
sediment, the entire structure has been preserved, and the seismic data and well logs
extend to 3000+ m below the present surface. Therefore, the Red Wing Creek structure
offers an excellent opportunity for comparison to Upheaval Dome.
The exterior structures present at the Red Wing Creek structure include a ring
depression and normal grabens (Brennan et al., 1975). The units in the ring depression,
either a syncline or graben, are between 175 and 65 meters lower than the expected
regional elevation. This downward displacement seems to offset the central uplift
(Brennan et al., 1975). The units in the ring depression are principally deformed through
normal faulting, with the fault blocks moving in towards the center as well as downward
(Brennan et al., 1975).

Shatter cones have been found more that 500 meters below the top of the central
uplift in the oil wells within the Red Wing Creek structure (Brennan, et al, 1978). But,
the lithologies involved in the Red Wing Creek structure are mostly carbonates and lesser
amounts of evaporites. In fact, shatter cones are usually found in dense, aphanitic rocks
such as carbonates, sandstone, quartzite, granite and gneiss (Deitz, 1972), lithologies
which are very different from the shales and sandy shales of the Moenkopi at Upheaval
Dome.
There appears to be a positive (+1.5 mgals) gravity anomaly associated with the
Red Wing Creek structure, however it is “about four townships in areal extent. The size
and relief anomaly indicates that it is principally an intra-basement feature.” It is not
known whether this anomaly is genetically associated with the Red Wing Creek structure
or not. The magnetic data shows no anomaly over the Red Wing Creek structure
(Brennan et al., 1975).
Other impact structures in sedimentary target rocks have had magnetic and
gravity data collected over them. One is the Gosses Bluff impact structure, about 160 km
west of Alice Springs in Australia. The Gosses Bluff structure is a roughly oblong
structure, approximately 14 by 10 km, with a prominent center uplift and a surrounding
synform formed in Ordovician, Devonian and Carboniferous sedimentary rocks. The
rocks present at Gosses Bluff have been brecciated and faulted at the surface and to
depth, with dipping beds being found as deep as 1300 meters (Milton, et al., 1972). The
Bouguer gravity map of the Gosses Bluff structure shows a strong (+4.5 mgal) high over
the structure, with a 1.5 mgal inversion centered on the structure, while the magnetic data
collected at the Gosses Bluff structure shows both positive and negative local anomalies
(Milton, et al., 1972).

Figure 30. Three stages in the evolution of a simple salt dome, and showing the typical
structures associated with a buried, still rising salt diapir. The extensional structures
expected over the diapir are not found at Upheaval Dome. Figure after Jenyon (1986).

Figure 31. Cross section of Upheaval Dome after the salt passed through the area,
showing convergent collapse of the structure. Note the stratigraphic placement of the
extruded salt sill above the Navajo Sandstone, the syndepositional thickening of the
Hermosa Formation and the strain ellipses above and below the structure. Figure courtesy
of Dr. Dan Schultz-Ela, and the University of Texas at Austin Bureau of Economic
Geology.

Figure 32. Cross section and plan views of Upheaval Dome, during and after the salt
piercement and detachment. Note the sub-radial thrust faults in the Pinch-off Stage plan
view and locations of listric faults in both cross sections. Figure courtesy of Dr. Dan
Schultz-Ela, and the University of Texas at Austin Bureau of Economic Geology.

Figure 33. Schematic cross section of the maximum cover impact (Latest
Cretaceous/Early Paleocene), showing original crater profile. Listric faults found in the
Wingate and Kayenta are extended to the surface. After Shoemaker and Herkenoff
(1984).

Figure 34. Cross section of Upheaval Dome, showing the depth of brecciation expected
in Shoemaker and Herkenoff's (1984) impact hypothesis, as seen in Figure 33. Figure
courtesy of Dr. Dan Schultz-Ela, and the University of Texas at Austin Bureau of
Economic Geology.

DISCUSSION OF HYPOTHESES IN REGARD TO FIELD RELATIONSHIPS
Deformation in the inner “crater”
The deformation within the crater is dominantly compressional. The thrust faults
which constitute the majority of this contractional regime are generally aligned in a sub-
radial, anastomosing, pattern. This pattern is described by Schultz-Ela (p.c.) as acting
like a camera iris, pinching off a salt stock and closing behind it, as shown in Figure 32.
However, the contractional sense of the central area could also be due to the central uplift
expected in an impact crater (see Figure 33). Uplifts such as these are seen in impact
structures like Gosses Bluff, Australia (Milton, et al., 1972), Red Wing Creek, North
Dakota (Brennan, et al, 1975, the Steinheim structure in Germany (Roddy, 1977(a)), in
modeled craters such as the Snowball explosion crater in Canada (Jones, 1977) and on
other planetary bodies such as the Copernicus crater on the Moon (Roddy, 1977(b)).
However, erosion has not modified the preceding examples to the extent seen at
Upheaval Dome, therefore, the style of the deep-seated structure beneath the central uplift
is unknown. In fact, the structure beneath the central uplift of all craters may be
fundamentally different, due to differences in the ground water levels, target rock types
and relative cohesiveness, and the size of the impactor. If this is the case, extrapolation
of the original Upheaval Dome structure based on a limited sample of other impacts may
impossible.
The well preserved, non-brecciated, relatively coherent Moenkopi beds in the
center are a problem for the impact hypothesis of Shoemaker and Herkenhoff (1983,
1984, Shoemaker, et al., 1993). In their 1984 paper, Shoemaker and Herkenhoff
hypothesize an impactor arriving at the end of the Cretaceous or at the beginning of the
Paleogene. They hypothesize that this impact left a 10 km crater on the Late Cretaceous
surface, approximately 2000 meters above the present ground surface. A crater this size
probably would have brecciated the rocks below it to the depth that is presently exposed,

as seen in Figure 34. While the Moenkopi in the center is deformed, it is by no means
brecciated, so an impact and crater as large as hypothesized by Shoemaker and
Herkenhoff probably did not occur. Shoemaker has since reconsidered the size and time
of the impact, hypothesizing that it occurred more recently, perhaps 50 to 100 meters
above the present ground surface (Herkenhoff, p.c.). But, the outcrop which Shoemaker
bases his shallow impact hypothesis on is ambiguous, and can be interpreted in a
multitude of ways (the outcrop is pictured in Figures 11a and 11b).
Shoemaker proposes that the Chinle at this outcrop shows evidence of normal
faulting linked to the modification of the transient crater, indicating that the present
ground surface was very close to the impact surface (Herkenhoff, p.c.). However, during
the Advanced Structural Seminar in the spring of 1993, Britta Gustavson, Todd
Osmundson and I mapped this outcrop as drag folds in the Chinle related to a White Rim
intrusion (see Figure 11). During my work with the JPL team in January of 1995, I
visited this outcrop again, with Ken Herkenhoff, and explained our (Gustavson, et al.,
1993) interpretation of it. He agreed that our interpretation was possibly correct.
The White Rim Sandstone Member of the Cutler Formation exploited zones of
pre-existing weakness as it intruded upward into the Moenkopi from its normal
stratigraphic position. This is seen in Figure 7, which shows the White Rim intruding
along bedding planes of the Moenkopi. It also infiltrates folds in the center and in places
breaks directly through apparently coherent beds.
The White Rim intrusions work well with the impact hypothesis. During the
compressional stage of the impact, the White Rim Sandstone could have become greatly
over pressurized by the compressional wave associated with the impact. If there was
even a small amount of water trapped in the pore spaces of the White Rim, this over
pressurization and shaking could have fluidized it and caused it to intrude upward as
seen. The White Rim dikes are generally not cut by the large thrust faults that occur in
the center, though they are often displaced along smaller, often mesoscale, faults. This

leads indicates that they were emplaced after the main compressional event, but before
the structure settled.
These intrusions do not fit into Schultz-Ela’s hypothesis. If a salt blob rose, it
should have triggered the White Rim to intrude upward before it passed though the White
Rim stratigraphic level. As the salt blob continued to rise, and it passed though the level
presently exposed, the White Rim should be faulted first by extension and then along the
contractional thrust faults. This does not occur, and is a major problem with Schultz-
Ela’s hypothesis.
The combination of the anthracite metamorphosed organic matter and the
apparently heat reset fission-tracks in the apatite crystals in the Mossback Member of the
Chinle indicate that at some time, Upheaval Dome was subject to a heating episode
(Giegengack, p.c.). This is consistent with the impact hypothesis. When an impact
occurs, much of the energy from the shock compression is deposited in the target rocks as
heat (Melosh, 1989, pg. 43). The duration of this heating event may be on the order of
days to months, and if so, is of sufficient time for the fission-tracks in the apatite crystals
to be reset and the organic material to cook (Giegengack, p.c.). If the apatite fission-track
dating technique is applied to the 150+ kg of rock that Giegengack had helicoptered out
of Upheaval Dome in January, 1995, it should be possible to determine for sure if a
heating event took place, thereby supplying strong proof of the impact hypothesis.
The shocked quartz found by Gustavson et al. (1993) may also indicate an impact.
However, with only two grains with poorly developed PDFs in one thin section, the
shocked quartz is by no means proof of an impact. Multiple grains in multiple formations
would be a strong indicator of an impact event at Upheaval Dome, however no other
shocked grains with two directions of PDFs were found in any other formation present at
the dome by Gustavson et al., Herkenhoff (p.c.) or myself.2
2 In late May of 1995, sixteen more grains of shocked quartz were found within the White Rim by
the Carleton College 1995 Advanced Structural Seminar. Eight of these grains had two, three or more sets

Transition between the inner and outer areas
The concentrically oriented TISOS (tightly-isoclinal, slightly overturned syncline)
which crops out on the east side (SE 1/4 of NW 1/4 B4), the west side (NE 1/4 of SE 1/4
B8), the northeast corner (SW 1/4 of SW 1/4 B3), and the southeast corner (SE1/4 of
SE1/4 B8), indicates the strongly contractional regime that occurred at the edge of the
present crater during the formational event. Erosion truncates this fold on its dome side,
however, its exterior limb becomes the limb of a concentrically oriented anticline, which
uplifts the Kayenta and Wingate on the edge of the dome. These folds were formed as
the surrounding sedimentary units slid inward during or after the uplift of the center
portions of the structure. This sliding inward resulted in the structural shortening of these
units, though both radial concentrically oriented folds and radial faults. The TISOS is the
innermost exposed of the concentrically oriented folds.
This area of extreme contraction at the edge of the crater fits both the detached
salt diapir hypothesis and the impact hypothesis. In both models, a strongly contractional
regime is expected in this area. In the detached diapir hypothesis, this contractional area
would be caused after the salt passed completely though the area, and the formations that
had surrounded the salt blob moved inward to fill the space it was evacuating. In the
impact model, it would be caused by the same convergent movement of the surrounding
areas inward after the evacuation of material from the center.
Outside of the TISOS, the Kayenta is extensively crumpled into a complex fold
ring approximately 700 meters wide beginning at the crater wall. This can be seen in
Figures 17 and 18. The Wingate underlying this area presumably is not deformed in the
same way. This can be seen in how the Wingate beds come out of the crater wall at a
relatively high angle in Figure 35, but do not appear to mimic the smaller parasitic-scale
folds that are found in the Kayenta.
of PDFs, with 50% of the PDFs approximately parallel to the ω{1013}, and π{1012} planes (Barbeau, et
al., 1995)

The majority of the deformation within the Kayenta in the transitional regime
probably occurred through slip displacement along and within the numerous shale
interbeds. The heterogeneous nature of the Kayenta allowed it to deform in a drastically
different way the Wingate could. The massive, homogeneous Wingate tends to form
relatively gentle, more open, folds directly below the Kayenta, and probably contains
extensive internal deformation that is obscured by the desert varnish. The Kayenta on the
other hand, composed of thin sandstone beds with shale interbeds, was able to use the
shale beds as a lubricant in its deformation. The Kayenta in the transitional area
deformed the way a stack of computer cards would deform, with numerous slip faces
between the beds, while the Wingate directly below deformed as a thick piece of rubber
might deform, with more large scale, open structures. Rather than trying to deform the
entire 80 meter thick Kayenta Formation as one formation, the shale beds allowed
sandstone beds within the Kayenta to deform almost individually, which allow it to
express the shortening which occurred much more visibly than the Wingate.
But the Wingate does deform differently at the base of the cliff. There, especially
on the north side, the radial folds have a very high amplitude and are closely spaced.
These show the radial expression of the circular shortening that occurred during the
Upheaval Dome event. The difference between the upper and lower Wingate
deformation style may indicate that the lower Wingate was separated from the upper
Wingate, either physically or lithologocaly, and deformed much more radically.
Two of these radial folds show particularly unusual features. One, on the west
side, shows the upper bed of the Chile broken perpendicular to the bedding plane (Figure
20). Another, on the north wall, shows what is apparently a bed within the Wingate
pinching out against the fold (Figure 23) , leading Schultz-Ela to call it a growth fold
(p.c.).
The broken Chinle anticline indicates the rapidity of the energy release during the
Upheaval Dome formational event. As the outer areas of the structure converged on the

inside, the Chinle anticline could not respond ductiley, so the upper bed snapped apart
like silicon putty does when it is rapidly deformed. This indicates that the deformation
must have occurred very quickly, without time for the units to slowly move into place.
Schultz-Ela uses the growth fold in the northeast corner as one of his arguments for the
deformation occurring over a long period of time. However, since the radial anticlines
are due to concentric circumferential shortening, which would have occurred only after
the detached diapir passed through the area, this does not indicate that the deformation
took place over a long period of time. If in fact this was a growth fold, the diapir must
have breached during early Wingate times, and the above formations would not have
been deformed. Since the overlying formations are deformed, this indicates that the bed
that appears to pinch out above the fold is not a growth fold.
Another structure found in the Wingate wall that shows the intense energy of the
compression event is shown in Figure 24. This shows the amount of shortening that
occurred in the crater wall in the SE 1/4 of kilometer square B1. The amount of
shortening, determined by measuring the length which it is deformed over and then
dividing it by the original length of the bed, shows that it has been shortened by 50%.
The thrusts in Wingate also show the contraction of the surrounding rocks
towards the center — as with all structures in the Wingate, the deformation intensity of
these faults decreases as distance from center increases — the faults die out within 900
meters of the center of the structure. These thrusts occurred as the circumference of the
units was shortened during the deformation. Since the Wingate is much more massive
than the Kayenta, this shortening was accommodated through large scale thrust faults and
mesoscale faulting, rather than the parasitic folds and shale interbed faults found in the
Kayenta.
Also found in the crater wall are scissors displacement normal faults. These faults
were found on the south wall of the crater. They extend for not more than 100 meters
from the wall and the displacement across them decreases away from the wall. These

faults are of a smaller scale than the thrusts just discussed, and probably helped to
accommodate the settling movement in the hanging wall of the thrust fault just to the
west.
All of these faults lie close to the center, indicating the differences between
brittle-type and ductile-type deformation in the upper formations at Upheaval Dome —
the greater the shortening, and the more massive the unit, the greater the chance that the
shortening was accommodated by faulting in addition to radial folds rather than folding.
This difference in the amount of shortening is expected in both the detached salt diapir
hypothesis and the impact hypothesis, since they both predict convergent movement
inward.
The mesoscale faulting that is so pervasive in the Wingate, Kayenta and Navajo
also accommodated some of the strain that occurred during deformation. Mesoscale
faulting of this scale is found at Colorado National Monument by Jamison and Stearns
(1982) in the Wingate Formation. Colorado National Monument is a large monocline
formed over a normal sense displacement basement fault, and is in fact related to the
Uncompahgre Uplift. At the Colorado National Monument mesoscale faulting decreased
dramatically as distance from a large (20 meter) displacement normal fault increased
(messoscale faults were present up to 150 meters from the fault) (Jamison and Stearns,
1982), much the same as the density of mesoscale faulting decreases as distance from the
crater increases at Upheaval Dome, though over a much greater distance (more than 1000
meters). These mesoscale faults may also allow for a great amount of displacement to
take place distributed among a great number of slip surfaces (Aydin, 1978; Aydin &
Johnson, 1978).
Deformation in the outer area
The large rim syncline dominates the outer areas of the Upheaval Dome structure.
It is thought to be caused by the removal of underlying material which moved into the

central uplift and some vertical movement of the salt in the impact hypothesis
(Shoemaker & Herkenhoff, 1983, 1984; Shoemaker et al., 1993) or by the removal of salt
from below and the faulting of the overlying rocks in the detached diapir hypothesis
(Schultz-Ela, p.c.; Schultz-Ela et al., 1994). See Figures 32 and 34 to see how the
syncline fits spatially into each hypothesis.
The graben faulting that occurs in Navajo and Kayenta in the SE 1/4 of NW 1/4
C9 indicates that the rocks in the syncline were rapidly deformed. If the deformational
event took place over a long time while the rocks were unlithified (as would happen in
the detached salt diapir hypothesis), then the syncline should have been able to
accommodate the tension plastically. The fact that the syncline was faulted indicates that
the rocks could not deform ductiley. In fact, the Navajo and Kayenta must have been
somewhat lithified because of the presence of the abrasive groove slickensides along this
fault. This indicates that the rocks could not bend fast enough in the syncline and
therefore faulted, sliding downward as the syncline extended.
The large scale, extensional, low-angle, listric normal faults found in the exterior
alcoves show the convergence along these fault planes of the exterior portions of the
structure toward the center. These fit both the detached salt diapir hypothesis (see Figure
31) and the impact hypothesis (see Figure 33), since both advocate convergent
compression.

Figure 35. The Wingate in the south-east corner of the crater, from east
of the overlook. These Wingate beds are the outer limb of the anticline
seen in Figure 15.

DISCUSSION
Detached Diapir
Although hypothesized for decades, and included on schematic drawings of
subsurface salt structures (Halbouty, 1967; Jenyon, 1986; Lopez, 1989), no buoyantly
detached salt diapir has ever been confirmed through public domain field evidence or
investigated at the surface. This is perhaps the biggest strike against the detached diapir
theory advocated by the University of Texas at Austin Bureau of Economic Geology.
However, their hypothesis does fit almost all of the observed structures at Upheaval
Dome.
Perhaps the most compelling reason for authors to advocate a salt diapirism cause
for Upheaval Dome is the presence of the relatively thick layer of Paradox evaporite
deposits in the Paradox Basin (Harrison, 1927; McKnight, 1941; Fiero, 1958; Mattox,
1968, 1975). No estimates of the original thickness of the Paradox Formation under
Upheaval Dome has been advanced by any of these authors. This makes determining
how much salt has been removed from the syncline difficult to determine, however,
assuming that the original evaporite thickness beneath the Upheaval Dome area was
between 550 and 600 meters (based on the Paradox deposition area from Figure 2), a
rough estimate can be made. The well log from the Husky Oil Company Buck Mesa #1
well shows that the present thickness to the evaporite beds is roughly 450 meters. This
indicates that roughly 100 vertical meters of salt could have moved out from beneath the
syncline, or a volume of about 1 km3.
The deformation in the central crater, and the thrust faults that form a sub-radial
pattern (see the plan view of the Pinch-Off Stage in Figure 32) indicates an underlying
organization of the shortening within the central crater. Shultz-Ela has compared these
structures to a camera iris, which opened up for and then closed behind a blob of rising

salt. This explanation is very appealing in that it provides an excellent kinematic model
for the structure. However, this model could work equally well in the impact hypothesis.
The tightly isoclinal, slightly overturned syncline (TISOS) can be explained in the
detached diapir hypothesis as an intense contractional structure resulting from the
collapse inward that must have occurred after the salt passed through. This could also
explain the contractional folds found in the Chinle, Wingate and Kayenta in the
transitional area.
The structures in the outer area, the very low angle pull-apart normal faults fit
with Schultz-Ela et al.’s hypothesis. In the syncline hinge, seen in the canyon on the
south side of Alcove C, the Wingate in faulted all the way to its base and the Kayenta is
directly on top of the Chinle. This shows that there was a large amount of extension from
the outside towards the center, something that is expected in Schultz-Ela et al.’s
hypothesis. Unfortunately, these structures don’t show multi-stage deformation, which
would be expected in a salt structure with episodic movement, except for one instance of
an unconformable channel fill west of Holeman Spring in upper Kayenta.
Despite never having been found on the surface in the field, detached diapirs have
been found in centrifuge models. However, Jackson, the experimenter in these models,
“no longer considers those models to be very good simulations of
structural development in upper crustal sedimentary rocks. The
overburden analog in those models deforms as a viscous fluid, which is
not really appropriate for rocks in which we clearly see faults. In addition,
the salt rises as a Rayleigh-Taylor instability. In that case, it will
ALWAYS rise if there is a density inversion (although perhaps very
slowly). Such behavior doesn't accord with rocks that we know have a
finite yield stress. In nature, salt may remain buried and static if the
strength of the overburden exceeds the buoyancy forces. [Also],
sedimentary layers don't undergo smooth thickening and thinning the way
a viscous material does, so that the configuration of the layers around the
salt bodies in the centrifuge experiments do not match observations from
nature. The only published model examples I can find are produced by
shortening subsequent to formation of a salt dome. However, they do
occur without that regional shortening in some other of our models.”
(Schultz-Ela, p.c.)

However, despite the way that Shultz-Ela et al.’s hypothesis fits the observed
structural features at Upheaval Dome, there are a number of problems that I see with their
hypothesis. Salt diapirs are driven by buoyant forces, due to the density differential
between the salt and the overlying country rock, but they are driven mostly from the
downward differential pressures of the overburden (Lerche and O’Brien, 1987). If the
diapir becomes buoyantly detached, the salt loses much of its motivation to move
upward, since no longer is there the pressure of the overburden pushing the salt
surrounding the diapir neck upward into the diapir body. The growth fold in the
Wingate that Schultz-Ela (p.c.) cites as proof of slow deformation of the structure pinches
out above a compressional radial anticline. This indicates that the salt would have passed
through before that portion of the lower Wingate was deposited. If that happened, then
the Kayenta and Navajo must not have been there, yet the Kayenta and Wingate are
deformed, therefore, the growth fold can not be a feature that indicates slow salt growth.
Their cross-section shows the salt flowing on top of the Glen Canyon Group — relatively
early piercement rather than waiting for the Cretaceous sedimentary rocks to cover the
area. If the salt was exposed at the surface during Triassic or Jurassic times, it probably
would have formed a salt sheet or glacier. This salt sheet would have left evidence of its
existence in the microstructure of the Glen Canyon Group, with intergranular cement
filling in casts of halite and gypsum crystals. These are not seen in the thin section.
The slickensides on the normal graben in the Navajo in the SE 1/4 of the NW 1/4
of kilometer square C9 indicate that the Navajo was lithified at the time that the southern
normal faults occurred. If it was lithified, then the salt would have had difficulty
breaking through the overburden, especially if the salt was detached from the mother
layer.
Also, in Schultz-Ela’s hypothesis, the White Rim intrusives would probably be
faulted, rather than just emplaced — in fact, they should be faulted somewhere along the

spires, completely separating sections of the dikes. This doesn’t occur in the field (there
are some small, collapse/secondary deformation faulting, but no large-scale thrust faults
cut the White Rim).
A final problem with Schultz-Ela’s hypothesis is that if it is a buoyantly detached
diapir, there are no others known in the world. His study group has considered that the
detached salt diapir might have been caused by a much small impact than described by
Shoemaker and Herkenhoff (1983, 1984). If this is the case, a salt diapir may have
formed due to the extreme weakening of the overburden after the impact. If the
conditions were right, this diapir may then have become detached.
Impact Hypothesis
The Red Wing Creek Structure in McKenzie County, North Dakota seems to be
about the same size as an impact at Upheaval Dome, as described by Shoemaker and
Herkenhoff (1983, 1984), would have been. However the structure at Red Wing Creek is
covered with a thick veneer of Jurassic and post-Jurassic cover (Brennan, et al., 1975).
At the Red Wing Creek Structure, they find a central uplift of highly deformed, steeply
dipping beds surrounded by a ring depression. Similar features would be expected at
Upheaval Dome, a large central area of uplift, fractured rocks and compression, a
transitional area of lesser contraction and an exterior area of extension into the center
resulting from the movement upward of the center material after the impact excavation.
Based on Shoemaker’s estimated late Phanerozoic cratering rate of 2.4 x 10-10
km-2 yr.-1 combined with the area of the Colorado Plateau (2.4 x 105 km2), Shoemaker
and Herkenhoff believe that there needs to be an impact somewhere on the Colorado
Plateau. (Shoemaker and Herkenhoff, 1984). This back-of-the-envelope calculation by
Shoemaker made him consider Upheaval Dome, with which he had been acquainted for
30 years, an impact crater (Herkenhoff, p.c.). This is a misapplication of statistical
methods; just because statistically there should be a impact crater on an area the size of

the Colorado Plateau does not mean that there is one. From this, and the extrapolation of
the listric thrust faults to the surface, Shoemaker and Herkenhoff hypothesize that the
area was covered with between 1000 and 2000 meters of sediment at the time of impact.
I would question these assumptions. I think that the features seen at Upheaval
Dome represent the much more near-surface effects of a smaller bolide. In fact it seems
more likely that the impact occurred in the Late Jurassic to Middle or Late Cretaceous,
with less cover, or much more recently, when the Middle Cretaceous units were exposed
during the Tertiary erosional event that formed the canyons. I believe that an impact
could not have produced the features seen at Upheaval Dome if it occurred with more
than 500 meters of cover above the uppermost presently exposed surface.
The complex deformation of the center and transitional area indicate that a great
amount of energy was transmitted through these units. This energy was enough to cause
severe folding and faulting, but not enough to cause chaotic deformation. In other words,
the energy caused a lot of movement, but it was orderly — it did not cause random
movement. This indicates that the present surface was far enough below the impact
surface to escape most of the brecciation expected, but was not buried deeply. Given the
size of the exposed structure, 1 km across the center, and 3 km across the transitional
regime, and taking into account the brecciation expected below an impact (Melosh,
1989), an original crater size of 2 to 3 km, 500 to 1000 meters above the present highest
surface is expected.
The impact hypothesis explains the thinning of the Wingate in the syncline and
the crumpling of the Kayenta quite well. In the impact model, the Wingate in the
syncline is structurally thinned along low angle faults relating to the convergence of the
outside materials into the inside. The Kayenta is crumpled due to the loss of area as the
surrounding rocks converge. The lack of thrust faults cutting the White Rim intrusives
fits with the impact hypothesis as well, as the White Rim would have been emplaced
during or after the thrust faults’ formation. The deformation of the lower Wingate

appears to result from a singular high energy event — more energy over a shorter period
of time than could be supplied by a salt intrusion. The slickensides along the normal
graben south of Alcove Spring show that deformation was after lithification of the
Kayenta and Navajo, and the graben shows that the rock couldn’t bend fast enough to fill
the space.
If Upheaval Dome is indeed the result of the impact of a midsized (100 - 500 m)
extraterrestrial object, I would expect that the structures seen on the exposed topographic
surface at Upheaval Dome were formed as follows. As the bolide impacted and
transferred much of its energy to a compressional shock wave and heat, the rock at the
exposed stratigraphic levels was driven downward by the shock wave, and then
isostatically forced upward. A strongly compressional regime existed in the center of the
structure as the underlying rocks moved upward to fill the space left by the removed
(vaporized) overburden. This movement upward was very rapid and occurred mostly
though faulting. As the underlying units moved upward, the rocks immediately
surrounding the center in the transitional regime moved inward to fill the space left by the
upwardly displaced central rocks. Because of their increased distance from the center
and the decreasing strength of the shock wave, these transitional rocks deformed by
means of folds, with some associated faults. The rocks in the exterior of the structure
also moved inward; their movement perhaps incorporating motion along ring faults in the
complex crater.
The impact hypothesis is not without its problems. Fiero (1958) reports low angle
uncomformities between the Chinle and Wingate that could indicate early
movement/multiple movements. There is limited shock metamorphism, and it is
contained within the White Rim. If the original impact crater was ~10 km in diameter
(Shoemaker and Herkenhoff, 1984), there should be shock metamorphic features present
within the Glen Canyon Group as well, since they would also have been directly under
the impactor. Despite these problems an impact model remains the most likely

hypothesis. Perhaps a shallower, smaller scale impact model better explains the origin of
Upheaval Dome than Shoemaker and Herkenhoff’s deeply eroded, midsize impact model.

CONCLUSIONS
Upheaval Dome has been an enigmatic structure since Harrison first published on
it in 1927. The structural deformation is complex and cannot be explained completely by
any of the hypotheses yet presented for the following reasons:
1. Upheaval Dome cannot have been caused by hydrotectonics because of the
lack of brecciation, the central compressional regime and the extension of
the exterior portions of the structure into the center.
2. Upheaval Dome cannot be a simple salt dome because of the lack of extension
over the central crater area, despite the well developed rim syncline and
the presence of the Paradox Salt at depth below the structure.
3. Upheaval Dome could fit into Schultz-Ela’s (Schultz-Ela et al., 1994; Schultz-
Ela, p.c.) buoyantly detached diapir hypothesis; however, the lack of
similar examples in the literature reduces much of the credibility of such a
salt tectonic history.
4. Upheaval Dome could represent the deeply eroded scar of a midsized complex
impact crater (Shoemaker and Herkenhoff, 1984). However there are no
crater scars from midsized impacts at this stage of erosion, so it is
unknown if Upheaval Dome represents such an impact structure.
It is my feeling that Upheaval Dome was produced by an impact event.
Hopefully, the seismic data collected by the Jet Propulsion Laboratory and the apatite
fission-track dating technique will help to answer this question. When complete these
studies should be able to ascertain the timing and relative size of the event, as well as the
amount of sedimentary cover present.
It is also my feeling that any midsized impact at Upheaval Dome would have
triggered some movement of the salt beneath the structure. Perhaps it is possible that an

impact at Upheaval Dome could have initiated the strange conditions that would allow a
salt diapir to form and become detached.
Upheaval Dome is a complexly deformed, enigmatic structure. Perhaps no
hypothesis will ever be able to fully explain all of the features present, but Upheaval
Dome is worth studying if for no other reason than to gain an appreciation for the
wonders of the natural world and humanity’s inability to explain much of what happens
on this planet.

ACKNOWLEDGMENTS AND THANKS
This work was supported under a number of grants from various sources. The
original Advanced Structural Seminar from which this project was spawned was a class
at Carleton College, and as such was supported through the Carleton College Geology
Department budget. The field work done in the spring of 1994 was financed in part by a
generous allocation from the Carleton College Geology Department Bernstein Fund, as
were costs for thin sections. Ed and Cindy Gustavson paid for an airline flight to Dallas,
TX, both to visit them and to visit Dan Schultz-Ela at the University of Texas at Austin
Bureau of Economic Geology. Ron and Judy Unger generously covered the costs of a
rental car while we were in Texas so that Britta Gustavson and I could visit her parents
and Dan Schultz-Ela. Partial support by the National Aeronautics and Space
Administration (NASA) Planetary Geology and Geophysics grant number 151-01-70-65
to the Jet Propulsion Laboratory (JPL) covered some transportation and the field costs
associated with my joining the JPL team while they collected their seismic data at
Upheaval Dome in January of 1995, as well as some of the costs associated with the
REFTEK training I attended in San Francisco. This grant also allowed me to see
Upheaval Dome from a helicopter, a thrill and experience that I will not soon forget.
Another Carleton Geology Department grant, also from the Bernstein Fund, paid for a
portion of my transportation from Minneapolis to San Francisco and from Salt Lake City
back to Minneapolis. My parents, Ron and Judy Unger also contributed funds that helped
to cover incidental expenses while in the field and in the reproduction of figures and
plates.
I would like to thank my comps advisor, Professor David Bice for introducing me
to Upheaval Dome and encouraging me to ‘limit’ my comps project. Britta Gustavson
taught me how to map during the Advanced Structural Seminar in 1993, and was always
willing to listen a description of the latest paper I read, as well as joining me in the field

during the spring of 1994. Her encouragement to me and obsession with Upheaval Dome
was and is always welcome. She read the numerous grant proposals I wrote and the
multiple drafts of this paper and helped me with edit them to their final form. She also
helped extensively in the preparation of my geologic map of Upheaval Dome.
Tricia Cornell and Professor Julie Maxson each read and supplied numerous
comments on a draft of this work; their help in fixing grammatical errors and making sure
that this paper was understandable was greatly appreciated.
Dr. Dan Schultz-Ela of the University of Texas at Austin Bureau of Economic
Geology gave freely of his thoughts and ideas during our brief visit to Austin. His (and
his family’s) hospitality was appreciated, as well as Dan’s help in our entering the J.J.
Pickle Research Center in Austin. He graciously supplied me with cross sections of the
detached diapir he created as well as reprints of salt tectonic articles written by members
of the BEG and his own slides of various structures within and surrounding the dome.
Ken Herkenhoff and Jeff Plescia of JPL as well as John Louie and Sergio Chavez-
Perez of the University of Nevada at Reno were instrumental in my participation in the
JPL seismic project at Upheaval Dome. Their vision and ability allowed geophysical
data to be collected in a National Park on an enigmatic structure. Working with Ken and
Bryan Kriens of California State University at Domingez Hills in the center allowed me
to discuss my observations with them and gain a better understanding of their impact
hypothesis. Bob Giegengack of the University of Pennsylvania was very forthcoming
with the work that he is doing on the apatite fission-track dating. Hopefully, when the
fission-track, seismic and gravity data processing is complete, this will add to the
knowledge of Upheaval Dome and help to fit one more piece into this very complex
puzzle.

AUTHOR'S NOTE, JUNE 15, 2021
I apologize for the quality of the figures, in particular the images, in this paper. The
research discussed in this work occurred more than 25 years ago, in the days of
Ektachrome. The photos from the original slides were scanned in the late 1990s, and
image quality is low, mostly to reduce the files to manageable sizes. I have every hope of
scanning the original slides, and updating this work, but this is what is available.
I made some minor grammatical edits in preparing this file, mostly removal of extra
spaces and periods. No intent was changed. Skimming this work, if I was writing it today,
I would perhaps make different word choices, and strengthen some portions; however, I
stand by the observations contained herein and the conclusions stated above.

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